The invention relates to a device for fastening and anchoring cardiac valve prostheses which is essentially formed of wire-shaped interconnected elements. In the folded up state it is allowed to be introduced through the aorta in a minimally invasive manner, and be anchored in the aorta wall after being deployed such that the implanted and secured heart valve prosthesis is allowed to adopt the function of the endogenous heart valve.
Heretofore, it did not succeed in a satisfactory extent to suggest a solution wherein both a secure sealing against the aorta wall and a secure retention can be ensured. On that occasion, such a device or such an anchoring support (stent) must be able to be folded up small enough in order to be stretched then at the site of implantation. With the known solutions a satisfactory enlargement will not be achieved with the appropriate tension force which is allowed to ensure such a retention. Proposals in which a form storage metal (memory metal) is to be used as well do not meet the requirements although an expansion takes place with these materials when a transition temperature has been reached and exceeded, respectively.
The solution as described in U.S. Pat. No. 5,411,552 cannot meet the requirements as well since a relatively instable object is to be used.
Another problem which is solved in an unsatisfactory manner so far is the secure attachment of an artificial or biological heart valve prosthesis. As a rule, the prostheses are lavishly sewn on to a stent. This is time-consuming and has to be carried out with great care in order to avoid damages.
Since the implanted heart valve prostheses have to be able to function over long periods the constructional design plays an essential role as well since damages and leakages can occur after the implantation otherwise which can result in life threatening states of the patient.
Hence, it is an object of the invention to suggest a device for fastening and anchoring heart valve prostheses which can be folded up small enough, and deployed at the site of implantation for a minimally invasive implantation through the aorta wherein a secure retention and a secure sealing with respect to the aorta wall are ensured.
According to the invention this object is solved with a device according to claim 1.
Advantageous embodiments and improvements of the invention can be achieved with the features mentioned in the subclaims.
Three identical pairs of arched elements each are substantial elements of the solution according to the invention which are interconnected in a configuration that is offset by 120°. The two arched elements of one pair are bent opposite to each other in a curved manner and connected by means of solid articulations. The solid articulations simultaneously meet the function of pivot bearings about which the arched elements of one pair can be swivelled similarly as with a seesaw. If a pressure force is exerted upon one of the arched elements, e.g. through the peristaltic action of the aorta, this arched element will be swivelled according to the same direction about the axis of rotation on the solid articulation. Simultaneously, the respective other arched element of the pair will be swivelled opposite thereto. Therefore, one of the two arched elements of the pair is then already pressed against the aorta wall increasing the sealing and the retention.
It is favourable to dimension the arched elements of a pair such that as far as possible the same lever relations are met with respect to the solid articulations forming the pivot bearings, thus rocker arms with an identical length or at least with approximately the same length will be formed.
The relative great distances of the solid articulations predetermined by the configuration of 120° of the pairs of arched elements, and the large surface areas covered by the arched elements as well are also advantageous wherein the distal arched elements do not only serve for fastening the heart valve prosthesis but also adopt a supporting function.
The mentioned advantages can still be improved by means of another curved arched element which is arranged in the distal direction.
On that occasion, the second distal arched element in its distal area is designed in a curved manner approximately like the first distal arched element. Partly, these two arched elements are designed and shaped such that they pass adjacent to each other, and gaps are formed between them. They are allowed to be interconnected at the same place at which the solid articulations are also arranged as a connection toward the arched element curved in the proximal direction. Hence, the formed gaps are open in the distal direction, and portions of the heart valve prosthesis are allowed to be introduced into the gaps and be supported.
At least one portion of a distal arched element is proximally retracted and guided up to a turning point in which adjacent arched elements are collected. With two distally arranged arched elements this applies to the respective distally outer arched element.
For stiffening and as a further possibility of fastening the heart valve prosthesis it is allowed to use an angular curved arched element being proximally retracted as well, the curved portions of which are located between the respective adjacent arched elements and are formed partly following the respective curvature. These arched elements with the distal ends thereof are secured to the one distally outer arched element or the respective distally outer arched element. Herein, the attachment also forms a respective solid articulation. These should still be located in a distance to the other solid articulations connecting one pair.
With a device being implanted and stretched over the pockets of a heart valve prosthesis then can be pushed in, held and supported there.
The construction of the arched element of the device according to the invention supports a heart valve prosthesis in a large-surface manner, and therefore with care. Additionally, it is allowed to be fastened with a substantially lower amount, for example by sewing.
The constructional solution enables a secure retention and the required sealing on the aorta wall, and with respect thereto, respectively. Pressing against the heart valve prosthesis from the inside by means of the arched element is advantageous for the sealing and for a reduced load of the heart valve prosthesis.
The device according to the invention can be implanted by means of a balloon catheter and can be deployed at the site of implatation. Advantageously, for the device is used a form storage metal as well having a suitable transition temperature by means of which an extension can be additionally achieved. For this, an alloy containing nickel and titanium can be employed which is available under the designation of Nitinol.
Moreover, the portion of the device supporting and holding the heart valve prosthesis can be implanted separately to a supporting body which is still referred to hereinafter with the description of an embodiment without reducing the advantageous properties. The implantation of this portion substantially consisting of the three segments having the heart valve prosthesis attached thereto then can operatively take place in a conventional form.
In the text that follows, the invention will be explained in more detail according to an embodiment in which